1 Field of the Invention
The invention relates to a clear detergent composition in gel form having opaque particles of active material uniformly dispersed therein, the compositions being useful for the cleaning of hard surfaces.
2. The Prior Art
Household detergent products traditionally have taken the form of a powder or a relatively low viscosity liquid. Powders have several disadvantages. They are dusty, difficult to accurately dose, susceptible to lump formation or "caking" during storage, and require more expensive manufacturing equipment than liquids. On the other hand, low viscosity liquids need to have all ingredients mutually miscible or otherwise must suspend the immiscible components. For those components that are mutually miscible, there frequently arises a chemical incompatibility. For instance, there may be incompatibility between anionic and cationic type compounds. Another example of incompatibility occurs between a reactive hypochlorite bleach and oxidation sensitive perfumes or surfactants.
Recently, there has been a trend to utilize thixotropic liquids which have the benefits of pourability and immobility characteristic of solids. Thixotropic liquid products can more easily suspend immiscible components and do provide some separation between aggressive and sensitive components.
One product category in which the thixotropic liquid form has found consumer acceptance is that of automatic dishwashing compositions. Subsequent discussion will focus upon such compositions. However, automatic dishwashing products are merely representative of numerous other product categories toward which the present invention is directed.
A large body of patent literature has emerged in the autodish area of detergent chemistry which provides relevant background to the present invention. Typical of automatic dishwashing technology are those thixotropic liquid compositions disclosed in U.S. Pat. No. 4,116,849 (Leikhim), U.S. Pat. No. 4,431,559 (Ulrich), GB U.S. Pat. No. 2 116 199A (Julemont et al.) and GB U.S. Pat. No. 2 140 450A (Julemont et al.). A characteristic of the foregoing art is use of clay materials as thickeners to suspend electrolytes of limited water solubility. Clays normally scatter light imparting a dull and opaque appearance to the thixotropic liquids. Thereby results compositions of aesthetically undistinguished appearance. A product of a more pleasing transparent character is not therewith attainable.
Liquids, unlike powders, have a serious problem with component compatibility. For instance, chlorine releasing bleaches, normally found in powdered formulations, oxidatively attack many co-components found in liquid automatic dishwashing detergent compositions. Oxidation sensitive components include perfumes, surfactants and dyes.
Fabric washing formulations have been reported which encapsulate the bleach to isolate the latter from oxidation sensitive co-components. Illustrative is U.S. Pat. No. 4,655,780 (Chun et al.). Encapsulates usually comprise one or more outer protective coatings surrounding a core of a solid chlorine releasing material. The core material may be a potassium or sodium hydrated dichloroisocyanurate. Coatings may be formed from fatty acids, soaps, waxes, and organic polymers or copolymers. Examples of encapsulated materials and processes for their preparation may be found in U.S. Pat. No. 4,078,099 (Mazzola), U.S. Pat. No. 3,015,128 (Somerville), U.S. Pat. No. 3,310,612 (Somerville), U.S. Pat. No. 3,389,194 (Somerville) and an article in Chemical Technology, Oct. 1974, pp. 623-626 by Goodwin and Somerville entitled Microencapsulation by Physical Methods". All of the foregoing are herein incorporated by reference.
Note should be taken that the encapsulated active materials aforedescribed were intended for powdered products as coparticulates with the base detergent granules. There was no consideration given to these particles as suitable in thixotropic liquids.
It is an object of the present invention to provide a cleaning composition of great aesthetic appeal and physically distinguished from that of powders, thixotropic liquids and opaque gels.
A further object of this invention is to provide a cleaning composition that incorporates the convenient flow features of a liquid with the component separating characteristics normally associated with powdered solids.
A still further object of this invention is to provide a gel that is clear and contains active materials protected from interaction with other components of the gel.
These and other objects of the present invention will become apparent as further details are provided in the subsequent discussion and Examples.